Cooling system for high power high frequency transmitters



Dec. 19, 1933.

L. A. GEBHARD 1,939,689

COOLING sYsTEM FOR HIGH POWER HIGH FREQUENCY TRANSMITTERS Filed Dec. 24, 1930 4 Sheets-Sheet l z 4. FT

/7 a m a g i 20 Z/ 1) l (D (DJ I i (D (D i J- /H L I l .Mi

IN V EN TOR.

ATTORNEY 9 1933. L. A. GEBHARD 1,939,689

COOLING SYSTEM FOR HIGH POWER HIGH FREQUENCY TRANSMITTERS Filed Dec. 24, 1930 4 heetsheet 2 flzwvra M ATTORNEY Dec. 19, 1933. L, A, GEBHARD 1,939,689

COOLING SYSTEM FOR HIGH POWER HIGH FREQUENCY TRANSMITTERS Filed Dec. 24, 1930 4 Sheets-Sheet 3 INVENTOR. $20M 8.. 945%0410,

BY a I ATTORNEY Dec. 19, 1933. 1.. A. GEBHARD 1,939,639

COOLING SYSTEM FOR HIGH POWER HIGH FREQUENCY TRANSMITTERS Filed Dec. 24, 1930 4 Sheets-Sheet 4 IN V EN TOR.

$044M a wlowd ATTORNEY WLM Patented Dec. 19, 1933 COOLING SYSTEM roa' men rownrtmon FREQUENCY 'rnansmr'rrsns :,Lonis A. Gebhard, wan-mag. o.

Application December 2 11qo.504;627 1 7 Claims; '(01. zed-17 My ihventionrelate's broadly to high frequencytransmitters and moreparticularly to a high power, high frequency electron tube transmitter. .One of the objects of. my invention is to pro- 5 vide an arrangement of'hij gh frequency electron tube transmitter adaptedfor highpower operation and having a high degree of transmission efficiency. i

Another object of, myv invention is to provide a m fluid cooling system fora highpower transmitter wherein isfa multiplicity of inductance coils connected with the; power. amplification circuits of the transmitter, the arrangement being such that high'frequencylosses due to the fluid cooling are substantially eliminated.

Still another object or my invention is to provide an arrangement offluid cooled'inductances in association with. 8 .high fpower electr'on tube systern in altransmittercirc'uit wherein the cooling 2g fluid is introduced'at points in the. inductances whichare at relatively low potential for eliminating losses of radiolf'requency energy.

Afurther object of my invention isto provide an assembly arrangementior a fluid "cooled in-f ductancesystem in a high power highv frequency transmitter wherein a; single insulatinghosecoil system. may be employed in the fluid coolinglfcircuit to both the high frequency coupling inductance and the high frequency loading inductances 0 of the high frequency, Os il ation circuits of an electrontube transmitter. 7

.Other and furtheriobjects of my invention re-.- side .inthe method ofconnectinga multiplicity or. lnductancecoils with a coupling coil in a fluid cooled inductance system for a high frequency transmitter in whichliighfrequency losses may bemaintained at a whilethe uniform temperature may. be maintained throughout the inductance'system under conditions'of high power operation as will be more fullyjset'fforth in the specification hereinafter following by reference to the accompanying dzawingswhereihi- 7 Figure l is an end'viewslriowing the arrange;- nient offluid cooled inductances inassoclation with the fluid-ccoledlcoupling' coil in -the" radio frequency amplification circuits of a high power transmitter according to-myf-i'nvention; Fig. 2 is an elevational view of the apparatus illustrated inFig'; 1; Fig. .3 isanenlargedzdetail view of'the 'flxture for establishing a fluid'connectiontwith the centralportiens .ofthe coupling inductance and the loading coilsof the transmitter; 4 "is atheoretical-view showing the circulating fluid paththrough. the coupling. coil and industances in the radio frequencysysoem of the transmitter;

circuit, which is generally grounded and the throughthe. insulating tubingicoil 4 out the disand Fig. 5 is a detail view showing-the method of interconnecting the low potential points of the loading coils for establishing a fluidcooling; path therethrough. V H

When the power output required from-aradio w transmitter reaches a certain point it isnecessary to employ fluid cooling; both for the anodes of the thermionic tubesused as well. as the. inductanee coils .in the output circuit and often the input'circuitsof the high power stages of amplification. When. the fluid. cooling is used at every high frequencies ofv operation ofthe transmitter severe losses are liable to occur at the points where the cooling fluid is admitted to, and dischargedfrom, the high potential cir- Bm romts. h wever, while at low radio frequency potential are generally at a high direct currentgpotential with respect to ground. It is necessary, therefore, to ieed the cooling fluid. through an insulating tubing coil and discharge. it through a similar coil. This coilis connected between the fluid supply and discharge low potential points .of theradio frequency cir-' cults. vrnnr nsuntihg, h coil must. beof snmcient length to' providefa fluid path sufi ciently; ohg and. ofhigh enoughresistance to prevent nnduewloss of electrical energy. in-the: drawings, the fluid cooled tubes are shown at 1 and lq withtheir fiuidcooling jackets a id- 2a., The fluid oolin forthe 'therrnionic tubes is obtained from source The circulat is passed up through; insulating tubing cpil ito thie -center of thecoil 5 From the center of a them-rid. path divides and passes to Jackets; 2 ,zand. 2a throughthe coil 5.. From the jachets it. returns throughcoil 5 to its center and charged. Cell 5 is arranged tohave suflicient inductance to cover the lowestefrequency band of the transmitter. Fixed coils '2, 8 and 9 are connected in. parallelw'ith coilsd by means of switching: system 10 to provideflthe proper. inductancefor the other frequency ranges of the transmitter. Antenna coupling obtained through coilll whichiis mounted inside of cell 5; Inductancecoils 7, 3 and 9 are each self-sus- 0 andare 'supported by sets-[of insulated pins indicated at 20 projecting. toward each other from theinsu-lated frame members -,21 which are intum supported upon the the frame.-22 of the transmitter. The fluid cooled circuitsof these 10 sulating tubes 12 and 13. The cooling fluid is supplied to the group of coils through insulating tube 14 to the central point on'coil 5 to which coil 4 is connected. The discharge is effected in a similar manner through insulating tubing 15 to the fluid circulating coil 4 at a point substantially coinciding with the center of coil 5. The fluid circulating paths in the center of coil 5 are shown more clearly in Fig. 3 where 5a and 5b are the tubes which form the conductor 01' coil 5. Parts 16 and 16a are connected to tubes. 5a respectively at the center of coil 5. The ends of these parts 17 and 17a are connected to the coil 4. Electricallyconductive tubes 18 and-18a enter into the sides of parts 16 and 16a. The open ends of these tubes are connected to the insulating tubes 18 and 180:, respectively. An electric terminal 8 located between parts 16 and 16:2

center of coil 5 for' provides a connection to the the anode potential. I p 7 The electrical and fluid cooled circuits of the complete system are shown'rn'ore clearly in Fig. 4.. In this'flgure the inductance coils and the insulating tubing coils have been expanded to more clearly illustrate the fluid path. That is to say; the inductances 7, 8 and 9 which consist of tubular members closedat opposite ends with fluid outlet and inlet connections adjacent the center thereof have been drawn inelemental form to show the mechanical equivalent of each of the'inductance-systems. Each of the induce tances'l, 8 and 9 have aninterior tube ,7a,8a and- 9a disposed therein and supportedlin-the partition members 7b, 8b and 9b-in eachof the inductances. The remote ends of the tubes constituting inductances 7, 8 and 9'are closed,en-' abling the fluid to be introduced adjacent the center of the tubes, circulated to one end thereof; returned through the central inner tubeto theopposite end 'thereof and then returned to a pointof discharge adjacent' the center of the tube.

cooling circuits of the inductance coils 7; 8 and J 9 in series.

' It will be seen in Fig. 4 that coils'l; s and 9 are successively connected to coil 5. Coil Shasl the ,a ode'potentialof tubes 1 and 1a connected'to it at all times. 'Any one ofthe coils '7, 8'and'9 are connected in parallel with coil 5 by meansof theswitches10 which may be angularly' shifted to engage sets of contacts 7c; or onthe in ductances 7, 8 and 9, respectively. The switches 10 "are actuated by rotatable shaft {member 28 to which crank 29 is connected on the outside of thepanel 30 which extends acrossthe front of v the radio transmitter. The coupling inductance 11 may be adjusted by means 'o fsh'aft 31 rotat able from crank 32 on their'ont of-panel 3Q; 'A counter 33 is actuated from gear 34 on shaft31 for-resetting the couplingto the desired'position for aipa'rticular transmission frequency: Coils 7,8 and 9 have the same direct current potential as coil 5. The center of thesecoils' will have ve y nearly the same potential as the center-ofcoil 5 as far as radio frequency is concerned and this will be nearly ground potential. Therefore by connecting the fluid cooling circuits to the centers ofcoils 5, '7, 8 and 9 it is'possible to get a very low loss system. In addition to this but one insulating hose coil 4 is necessary. This will supply a fluid inlet and discharge both for the anodes of tubes 1 and 2 for the cooling of coils 5,7,8and9.

In Fig. 4 the tubes have been shown diagrammatically with the anode jackets broken away in post 8 through the source of plate potential in-- dicated generally at 25 across which there is provided a by-path condenser 26 in series with inductance 27. v

While Iha ve described my invention in certain preferred embodiments I desire that it be understood that modifications may be made and that no limitations upon my invention are intended-except those which may ,be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows: I l. A tuning systemfor highfrequen'cy transmitters comprising a' coupling inductance and'amultiplicity of auxiliary inductances, each of said auxiliary 'inductances being constituted by tubularelements closed at each end thereof and having fluid passagestherethrough terminating at the approximate centers thereof and a series arranged fluid connection to the'saidapproximate centers of all of said inductances for eifecting a continuous co'olingjof said coupling'and r jflui'd'ipassageiof said coupling inductance'and' a Fig. 5 shows the method of connecting'the fluid cooling coil disposed in series with said inlet and discharge v connections forsupplying cooling fluid throughall of'said inductances-in a series path at points of minimum potential ofsaidfinductancesi" y y g I 3.'A tuning system for-high'frequency transmitters comprising a coupling 'indu'ctance con s'titutedby a dual tubular conductor, "a multiplicity ofauxiliary inductance'sfa dual passage cooling coil, and fluid connections betweenjthe M dual passage cooling'coil and the approximate centers of said auxiliary. inductancesand the central portion of said dual conductor inseries for circulating cooling fluid through said;in-

.ductances" and maintaining all of said induc' tances at; uniform temperature independent of t e rical connection thereto. U

4. 'A high frequency signaling system comprisiing apush-pull amplifier'circuitfa coupling inductance constitutedby a dual tubular conductor connected at the opposite ends thereoi with parts oi'said push-pull amplifier circuit, a multiplicity of auxiliary inductances each consisting of" a tubular conductive fmember closed atropposite ends thereof and having fluid passages intermediate said ends, and a fluid circulating tube connectingthe approximate centers of said auxiliary inductances with the central turns of the dual conductor constitutings'aidcoupling in ductance for supplying cooling fluid to said several inductances in series at'points of minimum potential thereof and a cooling coil in series with said fluid circulating tube.

5. In a high frequency signaling system, a push-pull amplifier circuit, a coupling inductance constituted by a twin tubular conductor having the ends thereof connected to portions of said push-pull amplifier circuit, a multiplicity of auxiliary inductances each consisting of a tubular conductor closed at each end thereof, fluid connections between the approximate centers of said auxiliary inductances with the central portion of said coupling inductances for maintaining all of said inductances at uniform temperature independent of electrical connections to said in ductances, a dual passage cooling coil connected in series with said fluid connectionsand means for establishing electrical connection with aselected auxiliary inductance independent of the paths for circulating cooling fluid therethrough.

6. In ahigh frequency tuning system for signaling circuits, a coupling inductance constituted by a tubular conductor, a push-pull amplifier circuit including a'pair of electron tubes having fluid cooled elements, fluid connections between the ends of the twin tubular conductor constituting said coupling inductance and the fluid cooled elements of the electron tubes; a plurality of auxiliary inductances each having different frequency characteristics and each consisting of tubular conductors closed at opposite ends thereof, and a series connected dual passage cooling coil disposed in the fluid cooling path extending from the central portion of said coupling inductance through the centers of each of said auxiliary inductances for maintaining said coupling inductance and said auxiliary inductances at uniform temperature.

7. A high frequency inductance system comprising a main inductance and a plurality of auxiliary inductances of differing frequency characteristics, a cooling coil, said main inductance being constituted by a twin tubular conductor having fluid inlet and outlet connections adjacent the centers thereof, said auxiliary inductances being constituted by concentric tubular members with fluid inlet and outlet connections and insulated tubular members con-' necting said cooling coilwith the inlet and outlet connections to said main inductance and the fluid inlet and outlet connections of said auxiliary inductances at the approximate centers thereof independent of electrical connections to said inductances for establishing a series circulating path for cooling fluid through all of said inductances.

LOUIS A. GEBHARD. 

